1. Field of the Invention
The present invention relates to an electrophotographic copying apparatus, and more particularly to a small-sized copying apparatus suitable for personal use.
2. Description of Related Art
Heretofore, various kinds of this type of copying machines have been proposed and put on the market. Most of the machines are, as shown in FIG. 1, provided with an exposure optical system b above a photoconductive drum a and a transfer charger c under the photoconductive drum a. Around the photoconductive drum a, a developing unit d, a cleaner e, an eraser f and a charger g are disposed with exposure space h, and the diameter of the photoconductive drum a is set (for instance, about 30 mm) as small as possible in order to be able to accommodate these devices.
Under such constructional arrangement, a transport path i of transfer materials which receive transfer process is formed conforming to the level of a transfer section positioned between the photoconductive drum a and the transfer charger c arranged under the photoconductive drum, and a fixing unit j is disposed at the terminal of the path i. A conventional copying machine of this type can be manufactured small and thin by making diameter of the photoconductive drum a as small as possible.
However, it is necessary for the photoconductive drum a to have a diameter which can provide sufficient circumferential length for disposing aforementioned various image forming devices since various image forming devices including the exposure optical system b are disposed only in the same conventional manner. Accordingly, there is a limit in manufacturing the photoconductive drum a in small size.
Furthermore, the image forming devices are bulky around the photoconductive drum a thereby causing the space of image forming section largely expanded. Under such arrangement, the fixing unit j expands more than the space of image forming section downwardly. Because of the reasons as mentioned above, sufficiently thin copying machine has not been introduced yet.
In order to reduce the number of image forming devices, it may be considered to perform one round of copying operation by properly using one charger as charger and transfer unit when the photoconductive drum a makes two cycles of rotations. However, the photoconductive drum a needs a circumferential length to cover the size for enabling copying operation, and therefore, the diameter of the photoconductive drum a needs to be, for instance, approximately 100 mm when A4 size paper is used for copying thus making the photoconductive drum more larger in size.
In the meantime, there is known a small-sized copying machine provided with a belt-shape photoconductor, in which the photoconductor is horizontally stretched so that image forming devices can be disposed without increasing size of the space at the locations above and below the photoconductor. However, there is no special consideration given to the arrangement of image forming devices and fixing unit, and consequently, the machine has not been manufactured sufficiently thin.